N. lewisi Habitats and Behavior 103 



around the nostrils dorsally and the anterior end of the lower jaw ven- 

 trally. It was not uncommon for the intruder to thrash about while pull- 

 ing its head from the opening of the retreat. 



Two larvae 49 mm and 51 mm TL, and two striped juveniles, were 

 introduced into a tank occupied by an adult so that adult-larval interac- 

 tions could be observed. Larvae were tolerated, and could venture into 

 retreats of either males or females. The adult animal became aware of 

 the larvae, possibly as potential food items, and often stalked them for 

 short distances. At no time, however, was a larva eaten, even when left 

 in the adult tank for two days. Gary Woodyard (pers. comm.) reported 

 a captive adult eating a juvenile, but the adult was not being regularly 

 fed. 



Two adults, a male 84 mm SVL and a female 95 mm SVL, and two 

 subadults, 62 and 59 mm TL, of Necturus punctatus were released into 

 a tank with an adult N. lewisi to observe interspecific interactions. The 

 two subadult N punctatus were immediately eaten. The adults were 

 attacked by resident N. lewisi, even by individuals that were somewhat 

 smaller in body size than the N. punctatus. During these attacks the 

 threat displays were the same as previously described, but the biting was 

 distinctly different. Interspecific bites were directed to the head and gills 

 of the intruder. The attacker would grasp the victim until it thrashed 

 loose. On one occasion, an intruding N. punctatus was dragged to the 

 retreat opening and held there for several minutes. During this time 

 there was violent thrashing, including a rolling or spinning motion by 

 the N. lewisi. Wounds from these bites appeared to be much more 

 severe than those inflicted on intruding N. lewisi. Deep lacerations were 

 always evident, and covered the entire head and gill rakers if the head 

 had been engulfed, or were across the snout and throat region if the 

 head was not engulfed. These wounds often became infected and were 

 fatal. 



Two N. lewisi, one juvenile 52 mm TL and one adult female 118 

 mm SVL, were introduced into a 10-gallon aquarium where two adult 

 N. punctatus were in residence. No attacks by the residents or by the 

 intruders were seen, although the N. lewisi went under rocks with resi- 

 dent N. punctatus. After one night the adult N. lewisi displaced one N. 

 punctatus. The displaced animal moved under, and remained under, the 

 rock with the other N. punctatus. The juvenile N. lewisi was moving 

 freely in the tank and never observed under rocks. 



DISCUSSION 



Necturus lewisi is a stream salamander that uses microhabitats 

 characterized by relatively high dissolved oxygen concentrations and 

 moderate stream flow. This is similar to other species of southern Nec- 

 turus that have been studied, including Necturus beyeri and Necturus 



